ImportanceMost women report moderate to severe pain after cesarean delivery. The extent of the ability of surgical wound infiltration with local anesthetic agents during cesarean delivery for the reduction of postoperative pain is uncertain.ObjectiveTo examine the efficacy of single wound infiltration with bupivacaine and adrenaline during cesarean delivery for the reduction of postoperative pain.Design, Setting, and ParticipantsThis randomized clinical trial was conducted between January 25, 2018, and May 30, 2020, at a university teaching hospital in Afula, Israel. A total of 288 women with singleton pregnancy who were scheduled for a planned cesarean delivery at term were randomized to receive single wound infiltration with bupivacaine and adrenaline during cesarean delivery (intervention group) or no single wound infiltration (control group) at a 1:1 ratio.InterventionsIn the intervention group, the subcutaneous layer was infiltrated on both sides of the wound by a mixture of bupivacaine and adrenaline before wound closure. Other perioperative techniques were similar between the groups.Main Outcomes and MeasuresThe primary outcome was mean pain intensity over the course of 24 hours after the operation, as measured by a visual analog scale (VAS) score ranging from 0 to 10 (with higher scores indicating greater pain intensity). To detect a mean (SD) reduction of 1 (3) points in the VAS score in the intervention group, 286 women were needed in total. Secondary outcomes included VAS score greater than 4 (indicating moderate pain) at 2 hours after the operation, use of rescue opioids, maternal satisfaction with the pain management procedure (using a scale of 1-5, with higher scores indicating greater satisfaction), duration of the operation, scar complications (hematoma, infection, and separation), and length of stay.ResultsAmong 288 women (mean [SD] age, 32.5 [5.1] years; all of Arab or Jewish ethnicity), 143 were randomized to the intervention group, and 145 were randomized to the control group. Demographic and obstetric variables were similar between groups. The primary outcome (VAS pain score) was significantly lower in the intervention group (mean [SD], 2.21 [0.56]) compared with the control group (mean [SD], 2.41 [0.73]; P = .02). In the intervention group, 11 women (7.7%) had a VAS score greater than 4 at 2 hours compared with 22 women (15.2%) in the control group (odds ratio, 0.47; 95% CI, 0.22-1.00; P = .05). In addition, compared with the control group, the intervention group had significantly lower postpartum use of rescue opioid analgesics (19 women [13.3%] vs 37 women [25.5%]; P = .009) and greater satisfaction with pain management (mean [SD] score, 4.65 [0.68] vs 4.44 [0.76]; P = .007). In the intervention vs control groups, duration of the operation, scar complications (hematoma, infection, or separation), and length of stay were comparable.Conclusions and RelevanceIn this study, wound infiltration with a single administration of bupivacaine and adrenaline during cesarean delivery reduced postoperative pain and opioid use and may have improved maternal satisfaction with pain management. These findings suggest the technique is efficacious, safe, and easy to perform.Trial RegistrationClinicalTrials.gov Identifier: NCT03395912